reqfix1-zimg-klein-validate8-green-20260412

Current validate8 closure.

Included:

• 8-case current-source validation record
• README quick start for HTP v75/v79
• Android HTP runtime bundles split as v75 / v79
• Hexagon NPU support section with Z-Image compare assets

Assets:

• stable-diffusion.cpp-android-htp-v75-20260412.tar.gz
• stable-diffusion.cpp-android-htp-v79-20260412.tar.gz

Remaining work:

• klein wf8 concat fuse optimization